Prevent NPE on commenting on lines with invalidated comments

Only check for a review if we are replying to a previous review.

Prevent the NPE in go-gitea#12239 by assuming that a comment without a Review is
non-pending.

Fix go-gitea#12239

Signed-off-by: Andrew Thornton <art27@cantab.net>

services/pull/review.go

@@ -29,7 +29,7 @@ func CreateCodeComment(doer *models.User, gitRepo *git.Repository, issue *models
 	// - Comments that are part of a review
 	// - Comments that reply to an existing review
 
-	if !isReview {
+	if !isReview && replyReviewID != 0 {
 		// It's not part of a review; maybe a reply to a review comment or a single comment.
 		// Check if there are reviews for that line already; if there are, this is a reply
 		if existsReview, err = models.ReviewExists(issue, treePath, line); err != nil {

templates/repo/diff/box.tmpl

@@ -155,7 +155,10 @@
 														{{if gt (len $line.Comments) 0}}
 															{{$resolved := (index $line.Comments 0).IsResolved}}
 															{{$resolveDoer := (index $line.Comments 0).ResolveDoer}}
-															{{$isNotPending := (not (eq (index $line.Comments 0).Review.Type 0))}}
+															{{$isNotPending := false}}
+															{{if (index $line.Comments 0).Review}}
+															{{$isNotPending = (not (eq (index $line.Comments 0).Review.Type 0))}}
+															{{end}}
 															<tr class="add-code-comment">
 																<td class="lines-num"></td>
 																<td class="lines-type-marker"></td>

templates/repo/diff/section_unified.tmpl

@@ -35,7 +35,10 @@
 			{{if gt (len $line.Comments) 0}}
 				{{$resolved := (index $line.Comments 0).IsResolved}}
 				{{$resolveDoer := (index $line.Comments 0).ResolveDoer}}
-				{{$isNotPending := (not (eq (index $line.Comments 0).Review.Type 0))}}
+				{{$isNotPending := false}}
+				{{if (index $line.Comments 0).Review}}
+				{{$isNotPending = (not (eq (index $line.Comments 0).Review.Type 0))}}
+				{{end}}
 				<tr>
 					<td colspan="2" class="lines-num"></td>
 					<td class="add-comment-left add-comment-right" colspan="2">